Although the public assumed the Jaguar XJS was a successor to the very popular E-Type it was in fact intended to be very different. It would be comfortable and luxurious – less a sports car than a sports tourer. This allowed it to use the same suspension layout as the recently introduced and supremely cosseting Jaguar XJ6. Externally the Jaguar XJS is most noticeable for its ‘flying buttresses’; sweeping from the top of the rear roofline down to the rear of the wings. Some criticize this feature but this was a common design for sports cars of the period such as Maserati and Ferrari. It also gave the quite large Jaguar XJS an excellent drag coefficient. Better than the E Type and allowing the XJS easily to attain over 150mph.
The Jaguar XJS’s engine was a fuel-injected version of the E-Type’s 5.3 litre V12, still one of the finest engines in the world today. It was thirsty though, and in 1981 the HE engine was introduced. With a modified cylinder head design and a better ignition system, fuel consumption was improved by over 20%. Transmission was the robust and smooth GM400 3 speed auto. The V12 auto remained in production for all 21 years of the Jaguar XJS production history.
In 1983 Jaguar introduced a completely new 3.6 litre straight 6 engine with 4 valves per cylinder. It was intended to take over from the venerable 4.2 litre XK engine in the XJ6 saloon. It was successfully trialled in the Jaguar XJS, mated to a 5 speed Getrag manual gearbox. The reduced engine weight and 5 speed box made up for reduced power. Compared with the V12 and resulted in a better balanced car.
In response to demand mostly from America, a cabriolet body was introduced at the same time followed by the V12 cabriolet in 1985. This body lost the flying buttresses, had a folding rear canvas roof and removable hard roof panels at the front. The Jaguar XJS retained rigidity since there was a central transverse roof beam. The strong roof gutter sections also remained, running fore and aft.
An automatic gearbox became available for the 6 cylinder XJS in 1987 in the form of a ZF 4 speed box with lock-up torque converter. In 1988 Anti-lock braking was introduced on all models (though not on the XJ12 saloon until 1991).
A full convertible was available on V12 models in 1989 using a semi-automatic electro-hydraulic system. The body had been modified with frameless door windows and substantial strengthening to make up for the loss of the steel roof.
A substantially revised coupé body was introduced in May 1991 referred to as facelift or part-facelift. This had fully glassed rear side windows, much-revised rear lamps and boot, and a different grille; amongst many other minor changes. The bumpers were still rubber mouldings over metal beams, topped with chrome finishers. The engine was much modernised and enlarged to 4 litres. The new body became available as a convertible for the 6 cylinder cars in 1992.
More demanding emissions regulations world-wide sapped the power of the V12 with the fitting of restrictive catalytic converters. Jaguar responded in 1993 by developing the V12 from 5.3 to 6.0 litres. Mated to an electronically controlled 4 speed automatic gearbox, it hugely improved responsiveness and opened up the gap again between the 6 and 12 cylinder cars. The body was revised with full plastic bumper skirts front and rear, and the convertible gained two rear seats.
In 1994 the “AJ6” 4.0 litre 6 cylinder engine was revised to become the “AJ16”. With better electronic management and breathing, the power was raised from 225bhp to 250. Closing the gap once more with the V12.
Alongside these mainstream XJS models, a more sporting variant was introduced. The XJRS was brought in initially in 1988 with TWR-designed suspension improvements and bodykit, but the same 5.3 litre engine. Then in 1989 the TWR-Jaguar joint venture, JaguarSport developed a much modified engine of 6 litres (not the same as the later, mainstream Jaguar 6 litre). With sequential injection and digital ignition power was increased to 318bhp. In 1991 the further revised XJRS used the facelift body with different bodykit mouldings and boot spoiler. When the 1993 Jaguar XJS 6 litre was introduced, demand for the XJRS declined due to its more expensive and more difficult to repair engine. Few more were produced.